TrES: The Transatlantic Exoplanet Survey

Intro : News : TrES Papers



TrES, the Transatlantic Exoplanet Survey, is a network of three small-aperture telescopes (pictured above) searching the sky for transiting planets. The network consists of Sleuth (Palomar Observatory, Southern California), the PSST (Lowell Observatory, Northern Arizona) and STARE (Observatorio del Teide, Canary Islands, Spain).

Our method of detection relies on the edge-on alignment of the extrasolar system. If a planetary system is oriented so that Earth lies near the plane of the planet’s orbit, then once per orbit the planet passes between its star and the Earth, causing a transit. This orientation is more likely for planets orbiting close to their parent star. During a transit, the planet blocks some of the light from the star, causing the star to appear dimmer. For Jupiter-sized planets transiting Sun-sized stars, the expected dimming of the star’s light will be about 1%, and the duration of the transit should be a few hours.

To look for such a transit, the TrES telescopes takes timed exposures of the same field-of-view all night for as many nights as the field is favorably positioned (usually around 2 months). When an observing campaign is completed for a particular field, the multitude of data are run through software which, after correcting for many sources of distortion and noise, produces light curves for thousands of stars in the field. Other software is run to analyze the processed data for variable stars and transit candidates. It takes two or more transits (or cycles in a variable star) to discern the period of the orbit (or the variability).

The TrES method therefore favors giant planets orbiting sun-like stars in close orbits. The results of successful radial-velocity planetary searches have shown that planetary systems of this type could be quite common.

See the STARE webpage for a summary of The Search for Exoplanets.


  • Number 5 is in the bag…, TrES-5!

  • We’ve found the largest known transiting planet, TrES-4!

  • We’ve found a transiting planet, TrES-3, with 1.9 Jupiter masses and an orbital period of only 1.3 days!

  • TrES-2, the first known transiting planet in the Kepler field and the most massive nearby transiting planet, discovered using small-aperture telescopes!

  • First direction detection of light from extrasolar planets! TrES group identifies thermal emission from the hot Jupiter TrES-1.

  • TrES group announces the discovery of a new detached M Dwarf Eclipsing Binary!

  • Discussion of identifying insidious blend contaminants common in
    wide–field transit surveys, such as TrES.

  • TrES Network Success: Transiting Planet Discovered! Transits of TrES-1 observered using 10 cm telescope.

TrES Publications